1. Field of the Invention
The present invention relates to a golf club shaft selecting system and a golf club shaft selecting method, and particularly, to a golf club shaft selecting system and a golf club shaft selecting method for selecting a golf club shaft suitable for a golfer corresponding to the characteristics of the swing of the golfer.
2. Description of the Background Art
Golf clubs are associated with various flexes and flex points of the shaft, and a golfer needs to select a golf club with the flex and the flex point suitable for him/her.
An example of a golf club shaft selecting system focusing on the flex of the shaft (EI: flexural rigidity) is described in International Publication No. W096/11726. It discloses measuring, for each golfer, one of a swing time, a swing speed (club head speed), a club head acceleration and a distortion amount of the shaft or measuring those items as well as the head speed.
An example of a golf club shaft selecting system focusing on the flexural rigidity distribution (El distribution) of the shaft is described in Japanese Patent Laying-Open No. 2004-129687. It discloses a system provided with a first analysis system having shaft behavior measuring means for measuring deformation behavior of the shaft during a swing, shaft EI calculating means for calculating an EI distribution of the shaft and shaft shape calculating means for calculating the deformation shape of the shaft during the swing, and a second analysis system having a swing classifying means for analyzing and classifying the swing of the golfer, in order to analyze the deformation behavior of the shaft during the swing, classify the swing of the golfer and select the shaft optimal for the golfer.
An example of a golf club shaft selecting system focusing on the torsional rigidity (torque) of the shaft is described in Japanese Patent Laying-Open No. 2001-070482. It discloses measuring a deformation amount of the shaft in a swing of each golfer, or measuring a head speed while measuring the deformation amount.
Another example of the torsion deformation measuring method is described in Japanese Patent Laying-Open No. 2003-205053. It discloses measuring a torsion deformation generated on the shaft in a swing of a golf club, and based on the time history data of the measured torsion deformation, providing a dynamic evaluation of the shaft including the torsion behavior of the shaft.
An example of a golf club shaft selecting system focusing on a toe-down (droop) amount in a swing is described in Japanese Patent Laying-Open No. 2003-284802. It discloses a method, in which a bending moment distribution on the shaft when a sample golf club is swung is measured, and based on the measured data and a flexural rigidity distribution of the shaft, five factors including “a toe-down amount”, which is a deflection amount of the shaft in a direction toward which the toe side of the club head is lowered immediately before the impact, are calculated. Based on the calculation result, a suitable or the optimal shaft for the golfer is selected.
Another example of a method for measuring the aforementioned “toe-down amount” is described in Japanese Patent Laying-Open No. 10-043332. It discloses that a television camera and/or optical detecting means are used when a toe-down amount of a golf club is measured.
However, in selecting a golf club (shaft) by a golfer, no clear selecting criterion has been available as to the selection of the mass and the shaft flex point (EI distribution) of the golf club shaft.